Treatment of lumber



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FRITZ IPFLEUMER AND 2:

., BY MESNE. ASSIGNMENTS,

OF DELAWARE.

nee s-2a To all whom it may concern; Be it known that .we, Frrrz Prnnor'inn,

' engineer, a subject ofthe A'u'strian Emperor,

7 many,

A. 48 Marienstrasse,

residing at Dresden,

FLEUMER, engineer,

Germany, and HERMAN- a subject of the Austrian Emperor at Dresden, A., 18 Johannstadterldfen'Gerhave invented new and usefullmprovements in the Treatment of Lumber; and'we do hereby declare the following to be a full, clear, and exact descript'on of the invention, such as will enable 0th rs skilled in the art to whichit appertains to make and use the same. f

v Our invention relates to the treatment of lumber and its particularobject is a method of treating light and porous lumber with a or rolling.

. gas pressure-acting upon the lumber from thus treatd contracts in section, in the direction of the fibers. The pressure view to obtaining a heavy, non-porous material having all the favorable qualities of 'high grade-lumber, specific wei assuming a' and particularly a high ht, great hardness, capacity of igh polish and great resistance to the influence of moisture. 1

We are aware that methods are known for rendering lumber more dense by compression; however such methods merely use mechanical pressure. produced by. pressing method consistsin subjecting the lumber at temperatures varying from 90 to 150' degr. C. to a high pressure-'either hydraulic or all sides. This treatment causes the tubular cellsconstituting the lumber structure to be considerably narrowed or to be compressed to a total: vanishing of the lon pores, that is-to say, the piece o lumber acting upon it from all sides absolutely exeludes the dan er of'crushin the structure of the wood, w 'ch is to be cared-with all processes based upon mechanicallcompresslon.

During the compression no gas orliquid -should enter into the longitudinal. pores, 'or else no excess pressure from without could be created nor wouldthe structure undergo any compression.

Accordingly our heir to be treated is covered with a layer of tough ela'sticmaterial absolutelyimpe vious enrati medium, ft} insin of 0 cap rubber or a.

residing In contradistinction thereto ourtudinal but not process iscarried out for instance in the following manner: Thelumfl 'rnna'rmnn'r or humans.

coating of soft metal such as lead, and a gas or hydraullc pressure of at least 200 kg. per square centimeter isallowed to act upon it at a temperature of from 90t0 150 degr. C.

This mode of carrying the process into effect is rather too expensive for commercial purposes, it being very difficult to render a comparatively thin coating absolutely im- Specification ofLetters ratentr- Patented Aug. 9, 11921.

7 r Y Application flle'dsSeptember 5, 1916. Serial Ito. 118,421.

pervious to hydraulic and even more so to 7 gas pressure. For commercial purposes the following far 7 simpler, cheaper and safer 'method can be recommended: l A vessel adapted to withstand high pressure, preferably an upright thick-walled steel cylinder being closed at one end and provided with a tight-fitting cover at the other end and inclosed in a heating envelop adapted to heat it to about 150 degr. C. is filled with a material which is viscous at this temperature." Pitch, asphaltum, resins, dense solutions of glue and the like are suitable for this purpose; we prefer employl ng ordinary asphaltum such as is used for street pavements. The asphaltum is freed from gases by several hours boiling and in case it should still be found too tough, some pitch is added. Into this tough mass the lumber is totally immersed and 1 fixed therein so as to be. prevented from rising to the surface. The pressure-cylinder \is then closed and the empty space above'the asphaltum is filled with compressed gas or a 1 liquid, preferably water is pressed in, until the required pressure-200 kgfper square centimeter at the least-is reached. When employing a pressure liquid, according to the progressing contraction of the lumber treated while if compressed gas is used, this is not necessary, as a rule, owing to its higher elasticit'y. v After the lumber has been subjected to the pressure for2 or. 3 hours, the pressure is released and the cylinder is opened. The lumber has been converted by compression into a considerable more dense product and volume reduction of one third or one half of its original'volume has taken place. In this way logs can be compressed, to be worked only after the compression. The process does not pertainto a final shaping, but, contrary tolthe mechanical pressingprocesses, merely' reproduces the raw heavy lumber.

The color, density and other qualities of the .product obtained depend upon the nafresh liquid should be introduced,

the temperature and pressure employed.

Higher pressure and higher temperature. produces an end-product of greater hardness and better polishing capacity.

it will be observed that when a liquid is employed for the purposes of our invention, such liquid is used in a condition of great density or viscosity, and for this reason the liquid does not impregnate the wood, but simply exerts pressure thereon externally.

Although it is possible to increase the density of highly porous lumber Without heating, merely by the action ot'hydraulic or gas pressure, nevertheless such densification as expressed by an increase of the specific weight, is not only far less than by simultaneously applying heat, but also extends merely to the porous layers of the lumber and at the end results in a mechani- .cal deterioration of the structure of the wood.

Example: Dry pineor fir-lumber of 0.62

specific density is heated for 2 hours in.

molten asphaltum to 150 degr. C. at a pressure of 230 kg. per square centimeter. The product obtained is a lumber having a specific weight of 1.45 and a chocolatevcolored section and being capable of being highly polished.

We claim i l. The method of treating lumber and the like to increase its density, which consists in subjecting such. materlal, at an elevated temperature, to pressure transmitted through a fluid in contact withsaid mate.

rial externally but of such nature as not to penetrate into it materially and, impervious to the pressure-generating medium.

2. The method of treating lumber and like materials to increase their density,

which consists inimmersing the material in. a llquid of considerable density or viscosity incapable of penetrating materially into the pores of the material, and applying pressure to such liquid While heating it to a temperature of from 90 to 150 centigrade.

3. The method of treating lumber and like porous materials to increase their density, which consists in enveloping the material in a protectiveliquid which closesthe pores on the surface of the material but does not enter said pores materially,and then applying pressure to said liquid to compress the material 'without impregnating it with said liquor. 1

4E. The "method for the densification of lumber which comprises heating the lumber submerged in a bath of molten asphalt for about two honrs at a temperature of about 150 C. and at a pressure of about 230 kg. per square centimeter. p v lln testimony whereof, we have signed this specification in the presence of two subscribing witnesses.

rnirz rrtnnimn. HERMAN Preterm-a. Witnesses: I

HENRY HASPER, ALLEN T. Jnnmnes. 

